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-rw-r--r--fs/bcachefs/rebalance.c366
1 files changed, 366 insertions, 0 deletions
diff --git a/fs/bcachefs/rebalance.c b/fs/bcachefs/rebalance.c
new file mode 100644
index 000000000000..568f1e8e7507
--- /dev/null
+++ b/fs/bcachefs/rebalance.c
@@ -0,0 +1,366 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "alloc_foreground.h"
+#include "btree_iter.h"
+#include "buckets.h"
+#include "clock.h"
+#include "compress.h"
+#include "disk_groups.h"
+#include "errcode.h"
+#include "move.h"
+#include "rebalance.h"
+#include "super-io.h"
+#include "trace.h"
+
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/sched/cputime.h>
+
+/*
+ * Check if an extent should be moved:
+ * returns -1 if it should not be moved, or
+ * device of pointer that should be moved, if known, or INT_MAX if unknown
+ */
+static bool rebalance_pred(struct bch_fs *c, void *arg,
+ struct bkey_s_c k,
+ struct bch_io_opts *io_opts,
+ struct data_update_opts *data_opts)
+{
+ struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+ unsigned i;
+
+ data_opts->rewrite_ptrs = 0;
+ data_opts->target = io_opts->background_target;
+ data_opts->extra_replicas = 0;
+ data_opts->btree_insert_flags = 0;
+
+ if (io_opts->background_compression &&
+ !bch2_bkey_is_incompressible(k)) {
+ const union bch_extent_entry *entry;
+ struct extent_ptr_decoded p;
+
+ i = 0;
+ bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+ if (!p.ptr.cached &&
+ p.crc.compression_type !=
+ bch2_compression_opt_to_type(io_opts->background_compression))
+ data_opts->rewrite_ptrs |= 1U << i;
+ i++;
+ }
+ }
+
+ if (io_opts->background_target) {
+ const struct bch_extent_ptr *ptr;
+
+ i = 0;
+ bkey_for_each_ptr(ptrs, ptr) {
+ if (!ptr->cached &&
+ !bch2_dev_in_target(c, ptr->dev, io_opts->background_target) &&
+ bch2_target_accepts_data(c, BCH_DATA_user, io_opts->background_target))
+ data_opts->rewrite_ptrs |= 1U << i;
+ i++;
+ }
+ }
+
+ return data_opts->rewrite_ptrs != 0;
+}
+
+void bch2_rebalance_add_key(struct bch_fs *c,
+ struct bkey_s_c k,
+ struct bch_io_opts *io_opts)
+{
+ struct data_update_opts update_opts = { 0 };
+ struct bkey_ptrs_c ptrs;
+ const struct bch_extent_ptr *ptr;
+ unsigned i;
+
+ if (!rebalance_pred(c, NULL, k, io_opts, &update_opts))
+ return;
+
+ i = 0;
+ ptrs = bch2_bkey_ptrs_c(k);
+ bkey_for_each_ptr(ptrs, ptr) {
+ if ((1U << i) && update_opts.rewrite_ptrs)
+ if (atomic64_add_return(k.k->size,
+ &bch_dev_bkey_exists(c, ptr->dev)->rebalance_work) ==
+ k.k->size)
+ rebalance_wakeup(c);
+ i++;
+ }
+}
+
+void bch2_rebalance_add_work(struct bch_fs *c, u64 sectors)
+{
+ if (atomic64_add_return(sectors, &c->rebalance.work_unknown_dev) ==
+ sectors)
+ rebalance_wakeup(c);
+}
+
+struct rebalance_work {
+ int dev_most_full_idx;
+ unsigned dev_most_full_percent;
+ u64 dev_most_full_work;
+ u64 dev_most_full_capacity;
+ u64 total_work;
+};
+
+static void rebalance_work_accumulate(struct rebalance_work *w,
+ u64 dev_work, u64 unknown_dev, u64 capacity, int idx)
+{
+ unsigned percent_full;
+ u64 work = dev_work + unknown_dev;
+
+ /* avoid divide by 0 */
+ if (!capacity)
+ return;
+
+ if (work < dev_work || work < unknown_dev)
+ work = U64_MAX;
+ work = min(work, capacity);
+
+ percent_full = div64_u64(work * 100, capacity);
+
+ if (percent_full >= w->dev_most_full_percent) {
+ w->dev_most_full_idx = idx;
+ w->dev_most_full_percent = percent_full;
+ w->dev_most_full_work = work;
+ w->dev_most_full_capacity = capacity;
+ }
+
+ if (w->total_work + dev_work >= w->total_work &&
+ w->total_work + dev_work >= dev_work)
+ w->total_work += dev_work;
+}
+
+static struct rebalance_work rebalance_work(struct bch_fs *c)
+{
+ struct bch_dev *ca;
+ struct rebalance_work ret = { .dev_most_full_idx = -1 };
+ u64 unknown_dev = atomic64_read(&c->rebalance.work_unknown_dev);
+ unsigned i;
+
+ for_each_online_member(ca, c, i)
+ rebalance_work_accumulate(&ret,
+ atomic64_read(&ca->rebalance_work),
+ unknown_dev,
+ bucket_to_sector(ca, ca->mi.nbuckets -
+ ca->mi.first_bucket),
+ i);
+
+ rebalance_work_accumulate(&ret,
+ unknown_dev, 0, c->capacity, -1);
+
+ return ret;
+}
+
+static void rebalance_work_reset(struct bch_fs *c)
+{
+ struct bch_dev *ca;
+ unsigned i;
+
+ for_each_online_member(ca, c, i)
+ atomic64_set(&ca->rebalance_work, 0);
+
+ atomic64_set(&c->rebalance.work_unknown_dev, 0);
+}
+
+static unsigned long curr_cputime(void)
+{
+ u64 utime, stime;
+
+ task_cputime_adjusted(current, &utime, &stime);
+ return nsecs_to_jiffies(utime + stime);
+}
+
+static int bch2_rebalance_thread(void *arg)
+{
+ struct bch_fs *c = arg;
+ struct bch_fs_rebalance *r = &c->rebalance;
+ struct io_clock *clock = &c->io_clock[WRITE];
+ struct rebalance_work w, p;
+ struct bch_move_stats move_stats;
+ unsigned long start, prev_start;
+ unsigned long prev_run_time, prev_run_cputime;
+ unsigned long cputime, prev_cputime;
+ u64 io_start;
+ long throttle;
+
+ set_freezable();
+
+ io_start = atomic64_read(&clock->now);
+ p = rebalance_work(c);
+ prev_start = jiffies;
+ prev_cputime = curr_cputime();
+
+ bch2_move_stats_init(&move_stats, "rebalance");
+ while (!kthread_wait_freezable(r->enabled)) {
+ cond_resched();
+
+ start = jiffies;
+ cputime = curr_cputime();
+
+ prev_run_time = start - prev_start;
+ prev_run_cputime = cputime - prev_cputime;
+
+ w = rebalance_work(c);
+ BUG_ON(!w.dev_most_full_capacity);
+
+ if (!w.total_work) {
+ r->state = REBALANCE_WAITING;
+ kthread_wait_freezable(rebalance_work(c).total_work);
+ continue;
+ }
+
+ /*
+ * If there isn't much work to do, throttle cpu usage:
+ */
+ throttle = prev_run_cputime * 100 /
+ max(1U, w.dev_most_full_percent) -
+ prev_run_time;
+
+ if (w.dev_most_full_percent < 20 && throttle > 0) {
+ r->throttled_until_iotime = io_start +
+ div_u64(w.dev_most_full_capacity *
+ (20 - w.dev_most_full_percent),
+ 50);
+
+ if (atomic64_read(&clock->now) + clock->max_slop <
+ r->throttled_until_iotime) {
+ r->throttled_until_cputime = start + throttle;
+ r->state = REBALANCE_THROTTLED;
+
+ bch2_kthread_io_clock_wait(clock,
+ r->throttled_until_iotime,
+ throttle);
+ continue;
+ }
+ }
+
+ /* minimum 1 mb/sec: */
+ r->pd.rate.rate =
+ max_t(u64, 1 << 11,
+ r->pd.rate.rate *
+ max(p.dev_most_full_percent, 1U) /
+ max(w.dev_most_full_percent, 1U));
+
+ io_start = atomic64_read(&clock->now);
+ p = w;
+ prev_start = start;
+ prev_cputime = cputime;
+
+ r->state = REBALANCE_RUNNING;
+ memset(&move_stats, 0, sizeof(move_stats));
+ rebalance_work_reset(c);
+
+ bch2_move_data(c,
+ 0, POS_MIN,
+ BTREE_ID_NR, POS_MAX,
+ /* ratelimiting disabled for now */
+ NULL, /* &r->pd.rate, */
+ &move_stats,
+ writepoint_ptr(&c->rebalance_write_point),
+ true,
+ rebalance_pred, NULL);
+ }
+
+ return 0;
+}
+
+void bch2_rebalance_work_to_text(struct printbuf *out, struct bch_fs *c)
+{
+ struct bch_fs_rebalance *r = &c->rebalance;
+ struct rebalance_work w = rebalance_work(c);
+
+ if (!out->nr_tabstops)
+ printbuf_tabstop_push(out, 20);
+
+ prt_printf(out, "fullest_dev (%i):", w.dev_most_full_idx);
+ prt_tab(out);
+
+ prt_human_readable_u64(out, w.dev_most_full_work << 9);
+ prt_printf(out, "/");
+ prt_human_readable_u64(out, w.dev_most_full_capacity << 9);
+ prt_newline(out);
+
+ prt_printf(out, "total work:");
+ prt_tab(out);
+
+ prt_human_readable_u64(out, w.total_work << 9);
+ prt_printf(out, "/");
+ prt_human_readable_u64(out, c->capacity << 9);
+ prt_newline(out);
+
+ prt_printf(out, "rate:");
+ prt_tab(out);
+ prt_printf(out, "%u", r->pd.rate.rate);
+ prt_newline(out);
+
+ switch (r->state) {
+ case REBALANCE_WAITING:
+ prt_printf(out, "waiting");
+ break;
+ case REBALANCE_THROTTLED:
+ prt_printf(out, "throttled for %lu sec or ",
+ (r->throttled_until_cputime - jiffies) / HZ);
+ prt_human_readable_u64(out,
+ (r->throttled_until_iotime -
+ atomic64_read(&c->io_clock[WRITE].now)) << 9);
+ prt_printf(out, " io");
+ break;
+ case REBALANCE_RUNNING:
+ prt_printf(out, "running");
+ break;
+ }
+ prt_newline(out);
+}
+
+void bch2_rebalance_stop(struct bch_fs *c)
+{
+ struct task_struct *p;
+
+ c->rebalance.pd.rate.rate = UINT_MAX;
+ bch2_ratelimit_reset(&c->rebalance.pd.rate);
+
+ p = rcu_dereference_protected(c->rebalance.thread, 1);
+ c->rebalance.thread = NULL;
+
+ if (p) {
+ /* for sychronizing with rebalance_wakeup() */
+ synchronize_rcu();
+
+ kthread_stop(p);
+ put_task_struct(p);
+ }
+}
+
+int bch2_rebalance_start(struct bch_fs *c)
+{
+ struct task_struct *p;
+ int ret;
+
+ if (c->rebalance.thread)
+ return 0;
+
+ if (c->opts.nochanges)
+ return 0;
+
+ p = kthread_create(bch2_rebalance_thread, c, "bch-rebalance/%s", c->name);
+ ret = PTR_ERR_OR_ZERO(p);
+ if (ret) {
+ bch_err_msg(c, ret, "creating rebalance thread");
+ return ret;
+ }
+
+ get_task_struct(p);
+ rcu_assign_pointer(c->rebalance.thread, p);
+ wake_up_process(p);
+ return 0;
+}
+
+void bch2_fs_rebalance_init(struct bch_fs *c)
+{
+ bch2_pd_controller_init(&c->rebalance.pd);
+
+ atomic64_set(&c->rebalance.work_unknown_dev, S64_MAX);
+}
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